The invention relates to polyacrylate esters with long-chain hydrocarbon and polyoxyalkylene groups, as well as to their use as surface active substances. In particular, the invention concerns polyacrylate esters with long-chain hydrocarbon and polyoxyalkylene groups with a reduced content of lower molecular weight components, as well as with a distribution of polymers which approximates the Poisson distribution.
In another aspect, the invention relates to the use of such polyacrylate esters as surface active substances, in particular, as emulsifiers for the preparation of emulsions from natural and synthetic oils and water and especially the use of the aforementioned polyacrylate esters for the preparation of W/O emulsions of natural and synthetic oils.
Copolymers of polyoxyalkylene (meth)acrylates and alkyl (meth)acrylates are known from the art. In Japanese publication 61/145254, organic and inorganic pigments are disclosed, the surface of which is treated with a copolymer which consists of 1% to 99% by weight of polyoxyalkylene (meth)acrylate and 1 to 99% by weight of alkyl methacrylate, wherein the alkyl group of the alkyl methacrylate has 6 to 22 carbon atoms. These copolymers increase the dispersibility of pigments that are treated therewith.
German Offenlegungsschrift 3,636,429 discloses polymeric surfactants based on copolymers of hydrophobic and hydrophilic monomers which contain, in copolymerized form,
(a) as hydrophobic monomers, compounds of the formula ##STR1## in which R represents H or CH.sub.3
X represents C.sub.4 to C.sub.20 alkyl or ##STR2## R.sup.1 represents H, C.sub.1 to C.sub.20 alkyl, halogen or ##STR3## n is 1 to 4 R.sup.2, R.sup.3 represent H, C.sub.1 to C.sub.20 alkyl, F, Cl, Br and PA1 Y is ##STR5## R.sup.4 represents H, CH.sub.3 or C.sub.2 H.sub.5 R.sup.5 represents H or C.sub.1 to C.sub.4 alkyl and PA1 m is 2 to 50. PA1 a1) saturated aliphatic alcohols with 4 to 22 carbon atoms, PA1 a2) unsaturated aliphatic alcohols with 8 to 22 carbon atoms, PA1 a3) alkyl phenols, the alkyl groups of which in each case have 8 to 12 carbon atoms or their oxyalkylation products with 1 to 4 oxyethylene and/or oxypropylene groups, and PA1 R.sup.1 is the hydrocarbon group of a starter alcohol, R.sup.1 OH, PA1 n is 2, 3 or 4 and has an average value of 2 to 3 in the average polyoxyalkylene group PA1 x has an average value of 4 to 50 in the average polyoxyalkylene group,
(b) as hydrophilic monomers, compounds of the formula ##STR4## in which R represents H, CH.sub.3,
In aqueous systems, above the critical micelle concentration, these polymeric surfactants form micellar structures, which, in the case of a suitable structure and in particular concentration ranges, are present as liquid crystalline phases (mesophases). The copolymers disclosed in German Offenlegungsschrift 3,636,429 are said to make possible a wide variation of mesophasic structures and stability parameters. The copolymers have surfactant properties and the water soluble compounds can be used in detergent formulations to enhance detergency. The copolymers can also be used to increase the viscosity of aqueous phases, the viscosity increasing effect being largely independent of pH.
Gel chromatographic analysis of the state of the art copolymers reveals a relative broad distribution of molecular weights, which may be responsible for a decreased surfactant effectiveness. As can be further demonstrated by NMR spectroscopy and gas chromatographic analysis, the copolymers contain appreciable portions of low molecular weight compounds. These low molecular weight portions consists of significant concentrations of residual monomers, as well as of low molecular weight compounds. It is assumed that the reason for this may be found in the polymerization parameters of the various monomers, which differ greatly from one another.
However, for various reasons, these low molecular weight compounds are undesirable. The low molecular weight portions detract from and decrease the surface active properties of the known copolymers, since they themselves contribute little if anything to these properties. The low molecular weight portions are also undesirable for physiological reasons, since they can lead to health impairment, such as skin irritations, sensitization, etc.
The removal of these interfering portions from the copolymers that represent the state of the art in an economic manner is not possible.